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White Rooftops

Howlett Hall, The Ohio State University

Can't Take the Heat? Paint the Town White (or Green)!

Maggie Kearns

October 26, 2016

Have you ever given much thought to the color of roof tops and how they are affecting the environment? Well, you should! It turns out rooftops have a pretty significant effect on air temperature, energy consumption, and surrounding ecosystems.

Urban Heat Islands

As you can imagine, these effects are dramatically increased in cities, which are literally made of rooftops! The combination of people, traffic, and buildings in cities tends to keep them running a few degrees hotter than surrounding rural areas. The name given to this phenomenon is urban heat island.

Urban heat islands are created on hot summer days when the sun beats down on buildings and pavement, increasing the surface temperature to 40-50 degrees hotter than the air temperature. The dramatic rise in the temperature of a city’s surfaces then causes the surrounding air temperature to rise as much as 22 degrees. Because of this cycle of increasing temperatures, cities are forced to consume greater amounts of energy trying to bring internal building temperatures down.

Not only does the surface temperature affect the air, but it affects stormwater runoff as well. Stormwater pouring down onto these hot surfaces can increase the temperature of the water by 30 degrees. Over time, this stormwater drains into rivers, lakes, and oceans, eventually causing their temperatures to slowly rise as well.

Urban heat islands set this snowball effect of bad consequences into action, so we have a few solutions for you!

Painting your Roof White

This may sound like a crazy idea, but it has proven to have serious results! While a traditional black roof may reach temperatures of up to 180 degrees on a 90-degree day, a white roof will only reach about 100 degrees. As a result, the internal temperature of the building will be just 80 degrees, keeping energy consumption down. You could see savings of up to 46% on electric bills, just by cooling your rooftop’s temperature!

The people at White Roof Project were inspired by these statistics and decided to start an organization solely dedicated to painting roofs and doing the research to back up their work. They have a goal to paint 5% of the world’s rooftops each year in hopes to cover every roof by the year 2030. Some pretty staggering research was done when they set this lofty goal. The White Roof Project found that reaching this goal could have total savings in CO2 of 24 billion metric tons. That’s equal to the amount of CO2 emitted by Earth in one year. What does that mean? This project could lead to results that would have the same effect as “turning off” the Earth for an entire year!

Green Roof Solution

With this solution you aren’t painting your roof, but planting it! Water proofing your roof and then covering it with vegetation has a host of positive effects. Not only does your roof become more aesthetically pleasing, but it has ecological, economical, and psychological advantages.

Covering your rooftop with plant life can do a great deal to help with stormwater management. Rather than the rain hitting the rooftop and running off, it is now absorbed by the plants. An added bonus? When the plants absorb the water, they also remove the pollutants from it!

Having vegetation as the first point of contact between your rooftop and a storm is like adding a protective layer! With plants doing all the work, protecting your roof and soaking up the water, your roof will have a longer life, saving you money on repairs and replacement in the future. The green covering will also keep the building’s internal temperature down, lowering energy costs.

Finally, it has been said that psychologically, adding green space to areas increases people’s quality of life. Just by covering your rooftop with plant life you could save money, save the environment, and make people happier!